Microvision

The Microvision was a hand-held cartridge based
game system sold by Milton Bradley between 1979 and 1981. It featured
a 16x16 monochrome LCD display, 12 key keypad and paddle control. One
unique feature of it's design was that not only did the cartridges hold
the ROM code for the game, they also contained the microprocessor, and
acted as an overlay for the screen and keypad.